Four subjects will be studied for 3 drug dosages and a placebo in a double-blind three way cross-over design. Effects of injected IV drug on lower esophageal manometry tube and pH electrode for 6 hrs after IV injection. After overnight fast an esophageal manometric catheter with an attached pH probe will be passed transnasally. After 30 minutes of baseline recording zacopride will be injected intravenously. LES pressure monitored for 6 hours after injection.